Revisiting the Importance of Sulfur Electrode-Current-Collector Interface in Lithium-Sulfur Batteries

Abstract

This work demonstrates that, in lithium-sulfur (Li-S) batteries, the presence of the carbon/binder domain is more crucial at the vicinity of the current collector rather than in the bulk of the electrode. The electrode composition at the current collector interface is showcased to significantly impact the energy density, rate performance, reproducibility, and mechanical attributes of the Li-S cells made thereof. The coating of a micrometric interlayer composed of carbon/binder at the current collector-electrode interface is shown to be a promising avenue for the formulation of the sulfur electrodes with a low dead mass and volume while preserving a low polarization and high sulfur utilization. The short-term spatial redistribution of the solid (dis)charge end-products is tracked revealing the preferential precipitation of the S and Li2S at large cavities and near the current collector, respectively. The non-uniform transformations inside the sulfur electrode is further corroborated by detecting and analyzing the precipitation waves inside a pressure electrochemical cell. Electrode-current-collector interface (ECCI): This study suggests that the discharge of sulfur cathodes is often limited by the quality of connection at the electrode-current-collector interface (ECCI, vertical dashed lines). A poor ECCI (red) causes higher internal resistance which ultimately results in heterogeneous Li2S deposition as an insulating layer and ends the discharge prematurely. Working to improve the quality of ECCI is an efficient way to improve LSBs overall performance (yellow).image